Magnetic holder for marking dies



July 17, 96 J. E. MUNN 3,044,394

MAGNETIC HOLDER FOR MARKING DIES Filed Dec. 2, 1959 2 Sheets-Sheet 1 INVENTOR. John E. Munn his ATTORNEYS July 17, 1962 J. E. MUNN 3,044,394

MAGNETIC HOLDER FOR MARKING DIES Filed Dec. 2, 1959 2 Sheets-Sheet 2 IL y 'll I Ii M l/ "M Wm 'M; )IIIIIII INVENTOR.

John E. Munn his ATTORNEYS United States Patent O 3,044,394 MAGNETIC HOLDER FOR MARKING DIES John E. Munn, Edgewood Borough, Pa., assignor to Jas. H. Matthews & Co., Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 2, 1959, Ser. No. 856,801 7 Claims. (Cl. 10128) vention pertains comprise a holder with a number of openings therethrough, each of a size to slidably receive a marking die, which is in the form of short metal bar, usually of square or rectangular section with a marking character on one end and an impact surface at its other. A spring ball detent in a wall of each die-holding opening engages a detent in the shank of the marking die to releasably hold the die in the holder with its lower marking end flush with or protruding a predetermined short distance below the holder and the top end of the die projecting above the body of the holder. There are of course many variations of this arrangement, and in some cases the impact end of the die is seated in the holder, so that the operator strikes the top of the holder instead of a projecting end of the die itself.

In many cases there is a row of die openings for individual characters, and at one side there is an opening for a larger multi-character die.

Such devices require careful and exact workmanship to set the spring ball detents therein, so that any detent ball will properly engage any recess in any one of the set of replaceable marking dies and exert the right degree of holding pressure. When the die is struck a hard blow to make an impression in metal, both the detent ball and the detent in the die are subject to damage because the edge of the recess in the die and the projecting periphery of the ball are subject to a shearing action until the ball of the detent is forced laterally into its socket.

The present invention has for its principal object to provide a holder in which permanent magnets are used to hold the dies in position.

A further object of this invention is to provide a tool holder in which the die forms a closed magnetic circuit with the permanent magnets so that the dies are securely retained in the holder.

These and other objects and advantages are secured by my invention as may be more fully understood from the following detailed description in conjunction with the accompanying drawings showing one embodiment of my invention. In the drawings:

FIG. 1 is a perspective view of a holder for several individual character marking dies and one multi-character die;

FIG. 2 is a longitudinal vertical section in the plane of line II-H of FIG. 1, but on a larger scale;

FIG. 3 is a transverse vertical section in the plane of line IIIIII of FIG. 1;

FIG. 4 is a fragmentary plan View of the mid portion of the holder with the cover removed, and with two marking dies in position, the die being shown in transverse section;

FIG. 5 is a perspective view of a single magnet removed from the holder; and

FIG. 6 is a side elevation of a typical die.

3,644,394 Patented July 17, 1962 In the drawings, 2 designates the 'body of the holder. It is formed of aluminum or other non-magnetic metal, aluminum being satisfactory because of its strength and its light weight. As here shown, it is generally rectangular in form and in transverse vertical section. The body itself has a central row of openings 3 therethrough, which are here shown as being square. They are separated by integral partitions 4, the body having end portions 5 forming one wall of the two end openings. Along each row of openings there is an elongated recess 6 with a ledge 7 forming the bottom of the recess. There is a side wall 8 forming the outer longitudinal wall of each recess 5, and the end walls 5 close the ends of these recesses.

Set in each of the recesses 6 on the shelf or ledge 7 is a series of permanent magnets 10 which are generally of horseshoe form with an upper leg or pole 10a and a lower' leg or pole 10b, there being a space or longitudinal groove 11 between the two legs or poles. One of these magnets is shown in FIG. 5. Each magnet is only slightly longer than the span of two openings and one separator, and the magnets on one side are directly opposed to those on the other with their poles confronting each other, but reversed so that a north pole at one side of the holder directly confronts a south one on the other side. The magnets on each side are retained in place by a rod 12 that extends through the spaces or grooves 11 in the several magnets, and which have theirends fitted into openings in the end walls of the body. At one end the rod has a slight head or enlargement 12a to keep it from being pushed through the body. The rods are of such diameter that they have only an easy working clearance in the grooves 11 in a vertical direction, but the grooves are deeper in a horizontal direction so that there is limited free play or relative motion of the magnets transversely of the length of the body. The length of the recesses 6 in relation to the length of the magnets is such that a multiple number of the magnets will easily fit therein so that their abutting ends will not be so tight as to prevent the free relative transverse movement of the magnets, but they will be confined against appreciable longitudinal movement in the body. If there are an odd number of openings 3, one magnet may be half-length, or the recesses 6 may extend further into the end Walls 5.

Where there is a special marking or multiple character bearing mark required alongside the longitudinal row of marks, the body may be provided with a lateral ofiset 13 between its ends with a single large rectangular opening 14 therethrough, as best shown in FIG. 4. At each side of this opening the olfset has a recess therein similar I to the recesses 6 into each of which is set a magnet 16 similar to magnet 10, but in this instance the grooves between the two legs or poles of the magnets are transverse to the length of the body. A pin 17, having its outer end screwed into the body, is provided, one for each magnet 16, each pin having its inner end extending into the groove in one of the magnets 16 andbeing in the same relation to the magnets 16 as are the rods 12 for the magnets 10, that is, they hold the magnets in place. loosely enough that they can move slightly in the body toward and away from each other.

The open top of .the body is covered with a cover of rubber or rubber-like resilient material having openings 19 top of the body a convenient distance and has a rearwardly-extending handle 22 rigidly attached thereto. The body also has pads or feet 23 at each corner that hold the bottom 'face of the body at a desired elevation above the metal plate, billet or other object to be marked.

A conventional marking die 24 is shown in FIG. 6. It has a shank that is beveled at its upper end to provide a. striking surface, and its lower end is usually slightly tapered and has a projecting marking or type surface 24d thereon. The shank here shown is square to have a sliding fit in the opening 3, and a here shown, the shank is just a small fraction of an inch larger than the -trans verse dimension of the separator 4, as seen in FIG. 4. The advantage of this is that the pole faces of the magnets 10 will be spread slightly when the die is inserted, and hence contact the sides of the'die shank, but when there is no die in the holder, the magnets bear against the separators 4 and cannot obstruct the openings 3. Each of the separators 4 is slightly cha-mfered at its top, and the edges of the magnets may also be chamfered. The dies themselves are of a magnetic or magnetizable material, usually steel. The rods 12 and pins 17 are preferably brass or other non-magnetic material. The permanent magnets 10 and 16 are of-a material such as the magnetic alloy of aluminum nickel and cobalt known als1 Alnico or some other strongly magnetic metal or a y.

In use, selected marking dies are pushed into the holder through the top, and forced downwardly until the marking end protrudes below the bottom or" the body 2. The initial insertion of the dies is relatively easy, since the magnets will initially separate rather easily. However, as the dies are moved down, they will close, or substantially close a magnetic circuit between the opposite poles of the magnets 10 at the two sides of the die shank. By having the magnets free to actually contact the sides oi the die shank, there is no air gap between the magnet poles and the die, thereby creating a very strong holding force to retain the die in position when it comes to rest after being inserted, and it will be retained against movement under all normal conditions of handling. However, when each die is struck in succession with a hammer to impress a mark in a work piece, the magnets will not eflfectively impair the force of the blow. By having magnets 10 no longer than is necessary to hold two dies, the magnets can adjust themselves to contact both dies, whereas a longer magnet might contact only two of three dies if the dies were not in absolute alignment, and thereby leave an air gap that would impair the holding forceof the magnet. A larger or multiple die inserted in opening 14 is held in like manner. a

While I have shown and prefer to have the magnets at each side of the tool shank in sections and self-adjusting in the manner described, efi'ec'tive results could be .secured if the magnets along one side only were selfadjusting and sectional, the important factor being that some of the poles of some of the magnets be movable rel,

atively to the die to the extent required to secure a substantially' closed magnetic field through each die.

While I have shown and described a specific embodiment of my invention, the construction and arrangement of the parts may be varied as the design, shape or numher of marking dies required may demand. One or more dies are removed and replaced with others as the required marking on the work pieces, such as date, code number or piece number changes.

I claim: 7

1. A marking tool for. impact die marking comprising a non-magnetizable body having an opening therein to receive a marking die, a pair of magnets in the holder with their poles at right angles to the axis of the opening at two opposite sides of the opening with unlike poles in confronting relation and between which the shank of a 4 marking die is positioned when the die is in the holder, at least one of the magnets being movable in the holder toward and away from the other.

2. A marking tool holder for impact die marking as defined in claim 1 in which the magnets are horseshoe magnetswith the two legs of the magnets in horizontal position, one above the other.

3. A marking tool holder for impact die marking as defined in claim 1 in which the magnets arehorseshoe magnets with the two legs of the magnets in horizontal position, one above the other, and means secured in the body xtending loosely into the space between the two legs for holding the magnets in place while enabling the magnets to move to a limited extent toward and away from each other.

4. A marking tool for impact die marking comprising a non-magnetizable body having an opening therein to receive 'a marking die, a pair of magnets in the holder having their poles at right angles to the axis of the opening one at each of two opposite sides of the opening with unlike poles in confronting relation transverse to the axis of the opening and between which the shank of a marking die is positioned when the die is in the holder, said magnets being relatively movable toward and away from each other, and means for limiting the movement of the magnets to a position where they obstruct the opening in which the die is to be received.

5. A marking tool holder comprising an elongated body of non-magnetic material having a series of diereceiving openings therethrough with transverse separat of horseshoe magnets in the two recesses with their poles positioned one above the other and with poles of the magnets on one side confronting unlikepoles of the magnets on the other side, said magnets being mounted in the body for limited relative movement toward and away from each other in a direction crosswise of the axes of the openings so that their poles may engage the shank of a die slidably fitted into one of the openings.

6. A marking tool holder comprising a body of nonmagnetic material having a series of die-receiving openings therethrough with separating partitions therebetween, the body having a recess therein along two opposite sides of the openings, a series of horseshoe magnets in the two recesses with their poles positioned one above the other transverse to the axes of the openings and with poles of the magnets on one side confronting unlike poles of the magnets on the other side, said magnets being mounted in the body for limited relative movement toward and away from each other so that their poles may engage the shank of a die slidably fitted into one of the openings, a rod extending lengthwise of each recess, the rod extending between the poles of the magnets in the recess through which it extends positioned to limit the relative movement of the magnets toward each other.

7. A marking tool holder comprising an elongated body of non-magnetic material having a series of sideby-side die-receiving openings therethrough with transv verse separating partitions therebetween, the body having a recess therein lengthwise of the body along each 1 side of the series of openings, a series of horseshoe mag,-

nets in the two recesses with their poles positioned one above the other in a direction transverse to the axes of the openings and with poles of the magnets on one side confronting unlike poles of the magnets on the other side,

said magnets being mounted in the body for l ited relative movement toward and away from each other so that their poles may engage the shank of a die slidably fitted into one of the openings, said partitions extending between the poles of the magnets and keeping them separated one from another.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS 796,324 Grunder Aug. 1, 1905 1,001,689 Rogers Aug. 29, 1911 1,221,815 Adams Apr. 10, 1917 1,419,662 Erdle June 13, 1922 

